If you're not going to use your own name as the name of your company (example: John Smith), you're going to need a fictitious business name, or DBA (Doing Business As). With a DBA statement, you can legally publish your business name everywhere: the phone book, your business cards, advertisements, directories, etc. You're putting yourself at risk without one.
Just as important is your ability to open a bank account with your business name. However, over 70% of people make mistakes when trying to file legal documents, so doing a DBA without help can be challenging.